This project will investigate how cell surface proteins move on the surface of a muscle during the formation of a contact with a nerve. The motions will be observed by a variety of novel fluorescence techniques, including fluorescence photobleaching recovery and time-lapse fluorescence video. Greatest emphasis will be placed on the behavior of fluorescence-marked acetylcholine receptors in cocultures of rat nerve and muscle cells. The related area of membrane motion on regenerating neurites in culture will also be examined by these techniques. This work is relevant to understanding synaptogenesis during development and to the processes of neural regeneration.